An An (played by Guo Biting), a single young woman of marriageable age, is an ordinary white-collar worker in an advertising company. She moved to get rid of the harassment of her ex-boyfriend. Her new neighbors are a pair of siblings. The elder brother Pan Xiaozhe (played by Duan Yihong) is a biology postdoctoral fellow who likes to use biological knowledge to look at all daily affairs, and the younger sister Pan Xiaoxing (played by Liu Yase) is optimistic and cheerful. In a competition for advertising proposals, Pan Xiaozhe, who often makes people laugh and cry on weekdays, unexpectedly helped An An with his biological knowledge, and An An was successfully promoted. An An's advertising company was acquired, and the young and handsome operations director Li Xia (played by Dai Liren) was airborne to the US headquarters. An An secretly fell in love with Li Xia. Reminded by her good friend Zhou Jiani (played by Xie Yilin), An An, who had been repeatedly frustrated in her relationship, realized that the rules of love are the same as the theory of evolution: the weak are eliminated and the fittest survive. She decided to ask Pan Xiaozhe for help and use the scientific knowledge of biology to help herself have a successful relationship...